Conversion of hydrocarbon oils



Aug. 3, 1937. c H ANGELL 2,088,987

' CONVERSION OF HYDROCARBON OILS Filed June 27, 1934 FRACTIONATORINVENTOVR CHARLES H. ANGELL BY L QRNEY Patented Aug. 3, 1937 PAT NTOFFICE,

, 2,088,987, i 'coNvERsIo or HYDROCARBON OILS Charles H. Angell,Chicago, Ill., assignor to Universal Oil Products Company, Chicago,111;, a

corporation of Delaware Application June 27, 1934, Serial No. 732,599

2 Claims. (01. 196-49) 5 invention particularly refers to an improvedprocess for the p-yrolytic conversion of hydrocarbon Ioilsu'a'ccompaniedby reduction of the residual liquid conversion products to coke andprovidesfor separation of the hydrocarbon oil charging stockfortheprocess, preferably comprising an oil of relatively wide boiling range,into"relativelyloW-boiling and high-boiling components, the latter beingsubjected to coking tom gether with residual liquid conversion productsof the process while all or'selected fractions of its low-boilingcomponents are subjected to conversion, together with'intermediateproducts of the cracking and i coking operations.

I have previously disclosed a cracking process wherein the hydrocarbonoilcharging stock for thecoperation may beintroduced into anintermediate point-in the" system whereby the charging stock or theproducts resulting from its relatively mild conversion 9 are separatedinto relatively low-boiling" and high-boiling. components, thelatter-being commingled with the residual liquid conversion products ofthe process and subjected therewith to further treatment 05 (including:coking, whendesired) while the total or selected fractions" of saidlow-boiling components are returned to further conversion :withinthesystem, together with intermediate products of the cracking andcoking operation. The present invention differs from the previousdisclosure primarily, in that the present case provides for effectingappreciable further vaporization of the liquid conversion products,under substantially reduced pressure relative to that at which they 35are formed, :souas "to recover therefrom desirable relativelylow-boiling components for fur ther conversion. within the system,without first" subjecting" the same: to the high temperature conditionsnecessary 'to'accom'plish coking of their higher boiling n'on -Vaporouscom ponents."xThe' present invention further differs from the previousdisclosure in that the present case is directed exclusively to coking ofthe non-vaporous residual liquid resulting 5 from" the aboved'e'scribedfurther vaporization of the liquid conversion products of theprocess and,ialso, intl'ie present invention, means are af forded forutilizing regulated quantities of the charging stock for-cooling hotvaporous prod.-

50 ucts ofthe coking operation sufficiently to remove therefrom, priorto' their fractionation for the formation of reflux condensate,heavycomponents" undesirable as cracking stock, including entrainedparticles of tar, pitch and similar 55 high" coke-forming materials,saidhigh-boiling components being commingled, with the nonvaporousresidual liquid and the high-boiling components of the charging stockand subjected to coking therewith.

The provisions of the present invention for separationof the chargingstock, prior to any appreciable conversion thereof, into relativelylow-boiling and high-boiling components to be subjected to separatetreatment, as above described, make it practically advantageous for thetreatment of hydrocarbon oil charging stocks of relatively wide boilingrange, such as crude petroleum, topped crude and the like, which containan appreciable quantity of relatively lowboiling fractions suitable ascracking stock as well as high-boiling fractions of a relatively highcoke-formihgnature which are not suitable for conversion with its lowerboiling components. 1

The charging stock-for the operation of the present process may alsoinclude, when desired, oils containing an appreciable quantity oflowboiling fractions within the boiling range of motor fuel,particularly in case such low-boiling fractions possess satisfactorymotor fuel characteristics, such asgood anti-knock value, etc'., since,by use of the features of the present invention, such desirablelow-boiling components of the charging stock may be removed withoutbeing subjected to conversion.

One specific embodiment of the present invention may comprise subjectinghydrocarbon oil recovered fromwithin the system to conversion conditionsof elevated temperature and superatmospheric pressure in a heating coiland communicating reaction chamber, withdrawing both vaporous and liquidconversion products from the reaction chamber, introducing the same intoa reduced pressure vaporizing chamber and commingling therewithhydrocarbon oil charging stock for the process, comprising an oil ofrelatively wide boiling range, in which vaporizing chamber furthervaporization of the liquid conversion products and appreciablevaporization of the charging stock is accomplished, whereby lowboilingand high-boiling components of the charging stock areseparated,withdrawing vaporous products from the vaporizing chamber and subjectingthe same to fractionation whereby their components boiling above therange of the desired final light distillate product of the process arecondensed as reflux condensate, supplying the, reflux condensatecomprising the afore-mentioned hydrocarbon oil recovered from within thesystem, to the heating coil for conversion, subjecting. fractionatedvapors of the desired end-boiling point to condensation, recovering theresulting distillate, withdrawing residual liquid remaining unvaporizedin said vaporizing chamber therefrom, subjecting the same to heating ina separate heating coil whereby it is quickly brought to a temperaturesufficient to effect its subsequent reduction to coke without allowingsufiicient time in the heating coil to permit the appreciable formationand deposition of coke therein, introducing the resulting highly heatedresidual liquid into a low-pressure coking zone wherein it is reduced tocoke and introducing the volatilized materials from the coking zone intosaid vaporizing chamber.

Several methods of supplying the charging stock to the system, whichwill be later more fully described, are within the scope of the presentinvention. In all cases, however, the charging stock is eventuallyintroduced into the vaporizing chamber, prior to any appreciableconversion thereof, wherein it comes into direct contact with heatedproducts from the reaction chamber and hot vaporous products from thecoking zone and is thereby subjected to appreciable vaporization, itshigh-boiling non-vaporous components commingling with the heavy residualliquid conversion products of the process and being subjected tosubsequent coking therewith while its vaporized lower boiling componentspass, together with vaporous products of the cracking and cokingoperations, to the fractionator of the system wherein at least a portionof said low-boiling components of the charging stock are condensed toform a portion 'l of said reflux condensate which is subjected toconversion.

It is desired to clearly distinguish this method of operation fromsimilar combination cracking and coking processes wherein the chargingstock is supplied to the fractionator of the system or to the crackingcoil or to the heating coil of the coking system. With charging stocksupplied to the fractionator its total components boiling abovethe'range of the desired final light distillate product of the'processwill be condensed with the reflux condensate formed in this zone andreturned therewith to the heating coil of the cracking system. This isnot desirable in case the: charging stock contains high-boilingcomponents of a high coke-forming nature which are unsuitable forconversion in the heating coil together with the lower boiling oils. Thesame applies when the charging stock is fed direct to the heating coilof the cracking system. This method of operation (supplying the chargingstock to the fractionator or direct to the cracking coil) is thereforeapplicable only to charging stocks which contain no appreciable quantityof heavy components of a high coke-forming nature. On the other hand themethod of operation wherein the total charging stock is supplied to theheating coil of the coking system is applicable only to charging stocksof a relatively high-boiling nature since it has been found undesirablein coking operations of this character to pass a mixture of relativelylow-boiling and high-boiling oils through the heating coil of the cokingsystem, as this ordinarily results in excessive vaporization and cokeformation in the heating coil. Aside from the low-boiling components ofthe charging stock serving no useful purpose and in many cases beingdetrimental when subjected to heating with the residual liquidconversion products and high-boiling components of the charging stocksubjected to coking, the low-boiling oils tend to overload the cokingsystem and they are not subjected by this method of treatment tosuitable conversion conditions for the production of high yields of thedesired light distillate product. While the methods and means providedby the present invention for supplying a hydrocarbon oil charging stockto the system are particularly desirable for the treatment of chargingstocks of relatively wide boiling range, the invention is not limited tothe use of such oils since there is no disadvantage in supplying eitherlow-boiling or high boiling charging stock to the vaporizing chamber andseveral of the specific methods for introducing charging stock to thesystem provided by the present invention are advantageous regardless ofthe characteristics of the charging stock since it serves as a coolingmedium for the hot conversion products from the reaction chamber or thehot vaporous products of the coking operation, or both, to assist inpreventing their excessive further conversion and to assist in effectingseparation of residual liquid products, suitable for coking, from thevaporous components of the products from the cracking and cokingoperation, including desirable low-boiling distillates and intermediateproducts suitable for further conversion within the system.

The accompanying diagrammatic drawing illustrates one specific form ofapparatus embodying the features of the present invention includingseveral alternative methods of supplying the: charging stock to thesystem. These alternative methods are not to be considered equivalentbut may be selected to suit the par-' ticular requirements of the oilundergoing treatment and the other operating conditions of the process.It will be further understood that the invention is not limited to thespecific form of apparatus illustrated and described. Referring to thedrawing, reflux condensate from thefractionator of the system, includingselected fractions of the charging stock, is supplied, as will be laterdescribed, to heating coil I wherein it is brought to the desiredconversion temperature, preferably at a substantial superatmosphericpressure, by means of heat supplied from a furnace 2 of any suitableform. The heated oil is discharged from the heating coil through line 3and valve 4 into reaction chamber 5.

Chamber 5 is also preferably maintained at a substantialsuperatmospheric pressure, which may be substantially the same orsomewhat lower than that employed at the outlet from the heating coil.Although not indicated in the drawing, the reaction chamber ispreferably insulated to prevent the excessive loss of heat therefrom byradiation so that conversion of the heated products supplied to thiszone, and particularly their vaporous components, may continue therein.In the case here illustrated, both vaporous and liquid conversionproducts are withdrawn from the lower portion of chamber 5 through line6 and valve 1 and are introduced into vaporizing and separating chamber8. His also within the scope of the present invention, although notillustrated, to separately withdraw vaporous and liquid conversionproducts from chamber 5, in which case the latter pass from the lowerportion of chamber 5, either alone or together with a regulated portionof the vaporous conversion products from this zone, and are directed, asjust described, into chamber 8 while the remaining portion orsubstantially all of the vapors are withdrawn from any desired point orplurality of points-in chamber 5 above the point of removal of theliquid conversionproducts and may bedirected either to chamber 8,entering this zone at any desired pointor plurality of points therein,or may be directed, all or in partgdirect' to fractionator H' by wellknown means not shown in the drawing.

Chamber 8 is preferably operated at a substantially reduced pressurerelative to that employed in chamber 5. Appreciable vaporization of theliquid conversion products supplied to this zone from the reactionchamber and appreciable vaporization of the charging stock, supplied tochamber 8 as will be presently described, is accomplished in this zone.Chambera also serves as a zone of separation for the vaporous productsof the cracking and coking operations and the vaporized components ofthe charging stock from the higher boiling non-vaporous oils supplied tothis zone, the latter including residual liquid products of the crackingoperation, highboiling components 01 the charging stock unsuitable forconversion in heating coil l and any components, includingentrainedtars, pitches and. the like, of a high coke-forming nature inthe vaporous products from the coking operation,

supplied to this zone as will be later more fully described. Thevaporous products of the cracking and coking operation, exclusive of anyhigh cokeforming components condensed and separated from the lowerboiling components of the vapors in chamber 8, and vaporized componentsof the charging stock are withdrawn from the upper portion of chamber 8through line 9 and valve I and introduced into fractionator I l.

The components of the vaporous products supplied to fractionator llboiling above the range of the desired final light distillate product ofthe process are condensed in this zone as reflux condensate. The refluxcondensate is withdrawn from the lower portion of the fractionatorthrough line l2 and valve l3- to pump l4: by means of which it is fedthrough line l5 and valve Hi to conversion in heating coil l,iin'the'manner already described. Fractionated vapors of the desired end-boilingpoint are-withdrawn, together with uncondensable gasproduced by theprocess, from the upper portion of fractionator I I through line I! andvalve l8and are subjected to con densation and cooling in'condenser l9.The resulting distillate and gas passes through line and valve 2| tocollection and separation in receiver 22. Uncondensable gas may bereleased from the receiver through'line 23 and valve 24. The distillatemay be'withdrawn from receiver 22 through line 25 and valve 26 tostorage or to any 1 desired further treatment. When desired, a regulatedportion of the distillate collected in receiver 22 may be recirculated.by well known means, not illustrated, to the upper portion offractionator H to 'serve as a;cooling and reflux-' ing medium to assistfractionation of the vapors.

The liquids remaining unvaporized in chamber 8, including the residualliquid products of the cracking operation, high-boiling'components ofthe charging stock unsuitable for: conversion in the heating coil ofthecracking system and'any high coke-forming'components or materialsentrained in the vaporous products from the coking operation,v arewithdrawn from the lower portion of this zone through line 21 and .valve28 to pump 29 byameans of whichthey are fed throughline 30 and valve 3|toh'eating coil 32... Theresidual liquid thus supplied to heating coil32 is heated to a temperature sufficient to eifect'its subsequentreduction to coke by means of heat supplied to a furnace 33 of anysuitableform; Preferably, the heating zone to which the residual liquidto be subjected to coking is supplied is of a .type employing relativelyhigh velocity through the heating coil and relatively high rates ofheatinput to the oil passing through the heating coil so that the oil isquicklyheated tothe'desired relatively high temperature without allowingit to remain in the heating coil 'forza sufiicient length of'time tocause any appreciable formation and deposition of coke in the heating.coil and/or in the lines leading from the heating coil to the cokingzone. The heated residual liquid is discharged from heating coil 32through line .34'and is supplied to coking chambers 35 and 35 by meansof lines 36 and 35', respectively,.con-' trolled by the respectivevalves 31 and 31. I

Coking chambers 35 and 35' are similar zones wherein reduction of theheated residual oils from heating coil 32 to coke is accomplished andwherein the. coke produced is allowedto' accumulate. It will beunderstood that one or any desired number of a plurality of cokingchambers may be employed and when two or more such zones are utilizedthey may bev simultaneously operated or, preferably, are alternatelyoperated, cleaned'and prepared for further operation so that theduration of the operating cycle of the process is'not limited by thecapacity of the coking zone. The coke may be removed from the chambersin any suitable well known manner, not illustrated, after theiroperation is completed. Chambers 35 and n 35' are provided with suitabledrain-lines 38 and 38', respectively, controlled by the respectivevalves 39 and 39 which may also serve, when desired, as a means ofintroducing suitable cooling material such as, for example, water orsteam into the coking chamber after its operation is completed and afterit has been isolatedfrom the rest of the system in order tohastencooling and facilitate'cleaning of the chamber.

vaporous products of the coking operation, which usually include somehigh-boiling compo nents of a high coke-forming nature as well asentrained particles of tars, pitches and the like, are withdrawn fromthe upper portion of chambers 35 and 35' through the respective lines40' and 40 controlled by the respective valves 4| and 4| and aredirected through line and valve 43 into vaporizing chamber 8 whereintheir components of a high coke-forming nature are separatedfrom theirlower boiling components, the

former passing with the other residual liquids from chamber 8 to heatingcoil 32, in the manner previously described, while the latter passtogether with the-other vaporous products from chamber 8 tofractionation in fractionator ll.

Hydrocarbon oil charging stock for the process is supplied through line44 and valve 45 to pump 46 by means of which it is fed through line-4land may be directed, all or in part, eitherthrough valve 48 in line 41into reaction chamber 5-or from line 41 through line 49 and valve 58into line 6 or through line 5| and valve 52 into line 42 or from line 5|through line 53' and valve 54 direct to vaporizing chamber 8. When thecharging stock is supplied to reaction chamber it is preferablyintroduced, as indicated in the drawing, into the lower portion ofthiszone to commingle therewith the conversion products supplied therefromtovaporizing chamber 8, in the manner already described,

the

serving to cool these products sufiiciently to retardtheir excessivefurther conversion and to prevent the formation and accumulation of cokein the lower portion of chamber 5 and subsequent 5 portions of thesystem, prior to the coking stage. It is, however, within the scope ofthe invention, although not illustrated, to introduce all or a regulatedportion of the charging stock into chamber 5 at any other desired pointin this zone and when introduced into an intermediate or the upperportion of the reaction chamber the charging stock may be subjectedtherein to relatively mild conversion conditions, prior to itsintroduction into the vaporizing chamber, by virtue of the heat impartedthereto from the heated products from heating coil I, with which it iscommingled in the reaction chamber, and the con version time afiordedthe charging stock in this zone.

When the charging stock is introduced into line 6 it commingles thereinwith the hot conversion products passing from reaction chamber 5 intovaporizing and separating chamber 8, serving to cool the same and retardtheir conversion. 25 When the charging stock is supplied to line 6 it iswithin the scope of the invention to introduce it thereto on either sideor on both sides of the pressure reducing valve 1, although only onepoint of introduction is shown in the drawing. When the charging stockis introduced into line 42 it commingles therein with the hot vaporousproducts from the coking zone, being thereby heated and subjected tovaporization, and serves as a means of cooling the hot vapor- 3i ousproducts from the coking zone sufliciently to .retard or arrest theirconversion and effect the separation therefrom, in chamber 8', of theirhigh-boiling components which it is desired to return to the cokingoperation.

40 In any case, Whether the charging stock is sup- .plied direct to thevaporizing chamber or is introduced thereto together with the conversionproducts from reaction chamber 5 or the vaporous products from thecoking operation, it is sub- ,45'jected to appreciable vaporization andis separated thereby, in the vaporizing chamber, into relativelylow-boiling and high-boiling components, serving at the same time toassist cooling of the heated products from the reaction cham- 50 her andfrom the coking zone to insure the separation therefrom of heavyresidual liquids.

It will be understood that the charging stock may be supplied to thesystem in any one or any desired combination of the manners describedand 55 it is also within the scope of the invention, when desired, toeither preheat the charging stock to below conversion temperature or tocool it to any desired degree in any suitable well known manner, notillustrated, prior to its introduction into 00 chamber 5, line 6, line42 and chamber 8.

Preferred operating conditions for accomplishing .the process of theinvention in an apparatus such as illustrated and above described may beapproximately as follows: The conversion tem- 65 perature, measured atthe outlet from the cracking coil, may range, for example, from 850 to950 F., or thereabouts, preferably with a substantially superatmosphericpressure at this point in the system of from 100 to 500 pounds, or there.7 abouts, per square inch. Substantially the same or somewhat lowersuperatmospheric pressure may be employed in the reaction chamberrelative to that employed at the outlet from the cracking coil and thevaporizing and separating chamher is preferably operated at asubstantially reduced pressure relative to that employed in the reactionchamber ranging, for example, from 100 pounds, or thereabouts, persquare inch down to substantially atmospheric pressure. The residualliquid to be coked may be heated in the heating coil through which it ispassed, prior to its introduction into the coking zone, to a temperatureof the order of 900 to 1000 F., preferably at a superatmosphericpressure of the order of to 150 pounds per square inch. The cokingchambers are preferably operated at substantially atmospheric orrelatively low superatmospheric pressure up to 100 pounds, orthereabouts, per square inch and preferably the pressure employed in thecoking zone is somewhat higher than that employed in the vaporizing andseparating chamber. The fractionating, condensing and collectingportions of the system may employ pressures substantially the same orsomewhat lower than the pressure employed in the vaporizing and.separating chamber.

As a'specific example of the operation of the process ofthe presentinvention as it may be accomplished in an apparatus such as illustratedand above described, with a charging stock comprising a heavy Californiacrude of about 16 A. P. I. gravity, regulated portions of the chargingstock are commingled with the conversion products withdrawn from thelower portion of the reaction chamber and with the vaporous productsfrom the coking operation, the commingled materials in both cases beingsupplied to the vapor izing chamber and the remainder of the chargingstock beingsupplied direct to this zone. Approximately 40% of thecharging stock is subjected-to coking together with the residual liquidconversion products withdrawn from the vaporizing chamber and theremainder is included with the'reflux condensate from the fractionatorof the system supplied to the cracking coil. A v

conversion temperature of approximately 925 F. and a superatmosphericpressure of about 300 pounds per square inch is employed at the outletfrom the heating coil with substantially the same pressure in thereaction chamber. The vaporizing chamber is operated at asuperatmospheric pressure of about pounds per square inch which issubstantially equalized in the succeeding fractionating,.condensing andcollecting portions of the system. The residual liquid to be subjectedto coking is quickly heated in a separate heating coil to an outlettemperature of approximately 950 F., at a superatmospheric pressure ofabout 100 pounds per square inch and the heated residue isintroducedintoalternatelyoperatedcoking chambers maintained at a superatmosphericpressure of approximately 50 pounds per square inch. This operation mayproduce, per barrel of charging stock, approximately 60% of motor fuelhaving an octane number of approximately 65, approximately 130 pounds ofcoke which is of good structural strength, uniform quality and has avolatile content of less than 6% and about 650 cubic feet of richuncondensable gas.

I claim as my invention:

1. A process for the conversion and coking of hydrocarbon oils whichcomprises subjecting oils recovered from within the system to conversionconditions of elevated temperatures and superatmospheric pressure in aheating coil and com municating reaction chamber, withdrawing vaporousand liquid conversion products from the reaction chamber and introducingthem into a reduced'pressure vaporizing chamber, introducing hydrocarbonoil charging stock for the process into the vaporizing chamber for thepurpose of cooling the heated products supplied to this zone and for thepurpose of subjecting the charging stock to substantial vaporization,withdrawing non-vaporous residual liquid from the vaporizing chamber,rapidly passing the same through a 7 second heating coil and thereinheating it sufiiciently to effect its subsequent reduction to coke,introducing the heated residual oil into a lowpressure coking chamberand therein distilling it to coke by the heat imparted thereto in thelastnamed coil, withdrawing the materials volatilized by the cokingoperation from the coking chamber and introducing the same into thevaporizing 15 chamber, withdrawing vapors from the vaporizing chamber,including vaporous products of the cracking and coking operationsremaining uncondensed in the vaporizing chamber and the vaporizedlow-boiling fractions of the charging stock, 20 subjecting the same tofractionation whereby their components boiling above the range of thedesired final light distillate product of the process are condensed asreflux condensate, subjecting fractionated vapors of the desiredend-boiling 25 point to condensation, recovering the resultingdistillate and supplying the reflux condensate,

comprising said oils recovered from within the system, to the heatingcoil for said conversion,

the process being further characterized in that 30 regulated quantitiesof the charging stock are introduced into the lower portion of thereaction chamber to commingle with and cool the conversion productssupplied from this zone to the vaporizing chamber.

2. A process for the conversion and coking of hydrocarbon oils whichcomprises subjecting oils recovered from within the system to conversionconditions of elevated temperatures and superatmospheric pressure in aheating coil and communicating reaction chamber, withdrawing vaporousand liquid conversion products from the reaction chamber and introducingthem into a reduced pressure vaporizing chamber, introducing hydrocarbonoil charging stock for the process into the vaporizing chamber for thepurpose of cooling the heated products supplied to this zone and for thepurpose of subjecting the charging stock to substantial vaporization,withdrawing non-vaporous residual liquid from the vaporizing chamber,rapidly passing the same through a second heating coil and thereinheating it sufiiciently to efiect its subsequent reduction to coke,introducing the heated residual oil into a lowpressure coking chamberand therein distilling it tocoke by the heat imparted thereto in thelast-named coil, withdrawing the materials volatilized by the cokingoperation from the coking chamber and introducing the same into thevaporizing chamber, withdrawing vapors from the vaporizing chamber,including vaporous products of the cracking and coking operationsremaining uncondensed in the vaporizing chamber and the vaporizedlow-boiling fractions of the charging stock, subjecting the same tofractionation whereby their components boiling above the range of thedesired final light distillate product of the process are condensed asreflux condensate, subjecting fractionated vapors of the desiredendboiling point to condensation, recovering the resulting distillateand supplying the reflux condensate, comprising said oils recovered fromwithin the system, to the heating coil for said conversion, the processbeing further characterized in that regulated quantities of the chargingstock are commingled with the stream of hot conversion products passingfrom the reaction chamber to the vaporizing chamber.

CHARLES H. ANGELL.

